1. Field of the Invention
The present invention relates to an image processing apparatus and method for efficiently synthesizing a plurality of image data while encoding the data, and a storage medium capable of being read by a computer in which an image processing program is stored.
2. Description of the Related Art
When editing images picked up by a video camera, as shown in FIG. 1, output image signals from two video cassette recorders (hereinafter abbreviated as xe2x80x9cVCRsxe2x80x9d) 110 and 112 are input to an image editor 114. An image signal obtained by editing the image signals is output to another VCR 116 in order to be recorded on a recording medium, such as a magnetic tape or the like.
FIG. 2 is a schematic block diagram illustrating the configuration of a camcorder (a video camera incorporating a recording/reproducing apparatus). In FIG. 2, an image pickup device 120 converts an optical image of an object into an electric signal. An A/D (analog-to-digital) converter 122 converts an analog signal from the image pickup device 120 into a digital signal. A compression circuit 124 performs data compression of data output from the A/D converter 122, and records the compressed image data on a recording medium 126. The output of the compression circuit 124 is also supplied to a digital interface (I/F) 128. The digital interface 128 conforms, for example, to IEEE 1394 standards. The image data is output to the outside in a format conforming to the standards.
Data reproduced from the recording medium 126 and the data input to the digital interface 128 are supplied to an expansion circuit 130, which expands the received data from a compressed state. Output data from the expansion circuit 130 is converted into an analog signal by a D/A (digital-to-analog) converter 132, and is supplied to a monitor 134 for image display.
Various image compression methods have been proposed and actually used. Many of these methods use both orthogonal transformation and variable-length encoding.
Conventionally, when synthesizing two images which are recorded in a compressed state as described above, image synthesizing processing is performed after completely expanding image data. FIG. 3 is a schematic block diagram illustrating a conventional image synthesis apparatus.
Compressed image data are input to input terminals 140a and 140b. Variable-length decoding circuits 142a and 142b perform variable-length decoding of the data from the input terminals 140a and 140b, respectively. Inverse orthogonal transformation circuits 144a and 144b perform inverse orthogonal transformation of outputs from the variable-length decoding circuits 142a and 142b, respectively, and output restored image data.
A system control circuit 146 controls the entire apparatus in accordance with the user""s operation through an operation unit 148. Particularly, the system control circuit 146 controls a coefficient generation circuit 150 so as to generate coefficients to be used when synthesizing the two image data. The generated coefficients are supplied to multipliers 152a and 152b. The multipliers 152a and 152b multiply the outputs of the inverse orthogonal transformation circuits 144a and 144b by the corresponding coefficients from the coefficient generation circuit 150, respectively. An adder 154 adds the results of the multiplication by the muntipliers 152a and 152b. That is, the adder 154 synthesizes the two images.
An orthogonal transformation circuit 156 performs orthogonal transformation of an output image from the adder 154. A variable-length encoding circuit 158 performs variable-length encoding of the output of the orthogonal transformation circuit 156. The output of the variable-length encoding circuit 158 is output to the outside from an output terminal 160.
As described above, conventionally, the two inverse orthogonal transformation circuits 144a and 144b are required, and orthogonal transformation processing is required when again encoding data after image synthesis. Accordingly, extensive hardware or software is required, and a long time is required for calculation.
The present invention has been made in consideration of the above-described problems.
It is an object of the present invention to provide an image synthesis apparatus and method capable of providing a smaller circuit and fewer signal processing steps than previously used, and a storage medium that stores program software for realizing the image processing method.
According to one aspect of the present invention, an image processing apparatus includes an input unit for inputting first image data and second image data different from the first image data. At least one of the first image data and the second image data is encoded while being subjected to orthogonal transformation processing. The apparatus also includes a transformation unit for transforming the first image data and the second image data into orthogonal transformation coefficient data, and a synthesis unit for synthesizing the first image data and the second image data transformed by the transformation unit.
According to still another aspect of the present invention, a storage medium capable of being read by a computer stores an image processing program, the program including an input step of inputting first image data and second image data different from the first image data. At least one of the first image data and the second image data is encoded while being subjected to orthogonal transformation processing. The program also includes a transformation step of transforming the first image data and the second image data into orthogonal transformation coefficient data, and a synthesis step of synthesizing the first image data and the second image data transformed in the transformation step.
According to still another aspect of the present invention, in a storage medium, capable of being read by a computer storing an image processing program, the program includes an input step of inputting first image data and second image data different from the first image data. At least one of the first image data and the second image data is encoded while being subjected to orthogonal transformation processing. The program also includes a transformation step of transforming the first image data and the second image data into orthogonal transformation coefficient data, and a synthesis step of synthesizing the first image data and the second image data transformed in the transformation step.